What they did
The poster, u/cleedek, watches Czech shows with a Vietnamese spouse and was pausing every few seconds to translate. The poster is a UX/UI designer, not a developer, so they asked Claude Code (running Opus 5.5 on medium effort) to build a Chrome extension that pulls the subtitles a video player loads, or takes an SRT or VTT file the user drops in, draws them as a layer over the player and hides the original ones. Translation goes through Google's built-in translator or an optional AI model (Gemini, Claude or a local Ollama model). Claude Code also handled the Chrome Web Store submission and made the store trailer video.
How it went
The poster says it took 6 to 8 hours from nothing to a published extension, including roughly 17 version updates through the store. The only part they did by hand was the store thumbnail, drawn in Figma. In the comments they explain that it grabs WebVTT, HLS and YouTube caption files and translates 30 lines at a time with 4 lines of context; TTML and automatic Netflix subtitles do not work yet. They released it free and open source.
Worth knowing
A commenter pointed out that line-by-line translation guesses badly at pronouns in languages like Vietnamese, and suggested passing a short cast list with each chunk. The poster agreed it was missing and plans to add it. Sites that use other subtitle formats will need a manual file.